1. Field
This disclosure relates generally to semiconductor packaging, and more specifically, to warpage control of packages using a package carrier assembly.
2. Related Art
Packaged semiconductor devices are typically manufactured using various process steps, including die bonding, wire bonding, and molding. Each of these steps may be performed at a different temperature. For example, die bonding may be performed at a temperature ranging between 125 to 150 degrees Centigrade, wire bonding may be performed at a temperature ranging between 175 to 200 degrees Centigrade, and molding may be performed at a temperature ranging between 175 to 200 degrees Centigrade. When package strips, particularly, thin package strips are subjected to these temperature variations at the different processing stages, the package strips can become warped during the post mold cure stage because of mismatches in the coefficient of thermal expansion (CTE) of the various materials used to create the package strips.
Warped package strips can create several problems. For example, warped package strips can get jammed in the magazine that may be used to load or off-load the package strips into various processing stations. Warped package strips may also get jammed at the on-loader and the off-loader equipment stations. Furthermore, the warped packages may cause problems with downstream processing, as well, such as ball attachment processing. In particular, solder balls may not attach to some of the individual packages on the package strip and some balls may not be formed correctly for some of the packages on the package strip.
Accordingly, there is a need for warpage control using a package carrier assembly.